How to solve the problem of flowmeter accuracy decline

There are many types of flow meters on the market, and the scope of utilization is also very common. The accuracy of the flowmeter has been determined when it leaves the factory. However, in actual applications, we will still show the results of reduced accuracy, and the level of change in the accuracy of each flowmeter is not the same. So how can we deal with the decrease in flowmeter accuracy? The following editor will give you a detailed introduction to the treatment methods for reducing the accuracy of the flowmeter.

1. Save installation

The accuracy of saving installation of this type of instrument does not require fluid calibration in some cases. The “dry standard” method is often used in the factory test, and the fundamental accuracy can be calculated. The calculation is based on the "extra value" provided by the demander, and the density of the medium can be actively compensated and intelligently performed. In this case, the key point is whether the location of the instrument device can meet the requirements of the instrument, such as a straight pipe section. If the length is not up to the request, the calculation of the additional deviation should refer to the specification book of the instrument. If the density of the medium is calculated manually, when the actual state of the fluid medium is different from the planned state, for individual gases, the flow performance value must be multiplied by a modification coefficient, and T, Z, and P are classified as additional tasks during the plan. The medium temperature, shrinkage coefficient, and medium pressure of the medium; t, z, p are distinguished as the medium temperature, shrinkage coefficient, and medium pressure under the actual task conditions. Obviously, the temperature and pressure of the fluid changes randomly in the real task, and the ultrasonic flowmeter can only compensate for the uniform value manually, and the deviation is obvious. A better measure is to take the intelligent instrument to actively compensate. For fantasy (or on the verge of fantasy) gas, this compensation accuracy is relatively high, and the accuracy of the performance mass flow or scale volume flow can reach ±1%.

Saving installation has certain requirements for straight pipe sections, and the additional deviation caused by unsatisfactory installation has a delineation for the installation of scale saving.

2. Positive displacement flow meter

For positive displacement flowmeters under the premise of realistic tasks, the additional deviation caused by the temperature and pressure of the fluid medium is usually caused by the influence of the temperature and pressure of the fluid medium on the volume of the metering chamber. When the material of the chamber is known, the volume change can be calculated, and the performance The reading of the meter is modified. The viscosity of the actual fluid may also have an effect on the meter readings, which should be considered based on the meter's specification. The length of the straight pipe section does not affect its accuracy individually, which is the protruding advantage of this type of instrument. This type of instrument shows the volume flow of the fluid under task conditions. What the user needs is the volume flow or mass flow under the standard conditions, and the density of the fluid needs to be compensated. At the beginning, the new flowmeter mostly used intelligent performance meters, and stopped the density active compensation.

3. Electromagnetic flowmeter

The principle of the electromagnetic flowmeter is based on Faraday’s electromagnetic sensing theorem. The pipe inner diameter (smooth area) of the sensor has an impact on the measured value. When the pressure and temperature of the fluid medium are different from the reference premise, the difference in the smooth area forms the transformation of the meter readings. Come out, otherwise a certain deviation will occur. This instrument has lower requirements for straight pipe sections. Pressure transmitter users should pay attention to it. There is currently no formula for modifying the straight pipe section. The meter measures the volume flow under task conditions. If the volume flow or mass flow under standard conditions is required, density compensation is still needed.

4. Turbo meter

This kind of instrument is more sensitive to on-site premises, and it is best for the user to fully satisfy its request in order to maintain the factory accuracy. When the temperature and pressure of the fluid medium differ greatly from the reference premise, the volume change of the sensor housing can be calculated according to the material of the sensor and the temperature and pressure plate, and the meter reading can be modified. When the viscosity of the fluid medium under the task condition is quite different from the viscosity of the calibration fluid, the modification should be stopped according to the viscosity modification curve provided by the instrument manufacturer. The turbo meter has certain requirements for the length of the straight pipe section of its high and low travel, and should be satisfied with the idea, especially when the user requests high accuracy. The instrument displays the volume flow under the premise of the medium task. If you want to know the standard volume flow or mass flow, you need to stop the density compensation. The measurement accuracy of the turbometer is high, and it is often used as a gauge to calibrate the task instrument.

5. Vortex flowmeter

The input type static pressure liquid level transmitter is relatively sensitive to the premises of the scene, and the user should be fully satisfied with its request in order to maintain the accuracy of the factory. When the temperature and pressure of the fluid medium differ greatly from the reference premise, the volume change of the sensor housing can be calculated according to the material, temperature and pressure plate of the sensor, and the meter reading can be modified. The vortex flowmeter has a higher request for the length of its upper and mean straight pipe section. It should be satisfied with the idea, especially when the user requests high precision. The instrument displays the volume flow under the premise of the medium task. If you want to know the standard volume flow or mass flow, you need to stop the density compensation.